If you treat them in the same manner, you could use the Rescorer
class to filter out the music results. Myrrix also has access to Rescorer(s)
For instance, this Rescorer
example from the Mahout in Action book filters out from the recommendations the books that are not in stock. You would do something similar where you would keep (somehow) track of which item ids are music and then use that information in the Rescorer
to filter them out so they don't get recommended.